Due to an unexpected wealth of players, it appears that I'll be starting off my new Age of Worms campaign with seven or eight players rather than the anticipated four or five. Anyone have any recommendations for scaling up the Whispering Cairn so that the characters don't steamroller over the existing foes?

Once I get into the later adventures, I can just modify them as per having a higher-level party, but for now I'd like to still provide my players with a reasonable challenge.

Here's one way to think about it: if the original adventure was designed for 4 players, and an encounter has 4 monsters, obviously the intent was for there to be 1 monster per player. So if you have 7 players instead of 4, increase the number of monsters to 7 also, to keep the ratio (monsters / players) the same.

Another method would be to keep the ratio of monster hit dice per player the same. This might work out better at higher levels.

There are also rules in the DMG for calculating 'challege rating' (CR) - so the idea here would be to keep CR the same as players increase. But the CR rules break down at higher levels.

Final option - wing it! Before the game, determine if an encounter should be 'easy' (two or three rounds of combat), 'medium' (3-6 rounds) or 'hard' (over 6). If your PCs are on the verge of finishing your 'hard' encounter at round 3, have a bunch more bad guys appear charging through the door!

Similarly, if your 100HP dragon is expected to last 5 rounds, and the barbarian in the group crits for 150 in the first round, give the dragon 200 more hp (or ignore the hit points and let it die after the next big hit that happens during or after round 5 - just don't let the players know what your doing).

My group has seven characters in the party (32-point buy) and I haven't had to scale anything up so far. We are currently in Gathering of Winds and there have been multiple character deaths, 3 in the Whispering Cairn alone.

I, too, recently began an Ages of Worms adventure with 7 players using a 32-point buy. My group is mostly very experienced players. We are finishing a scaled-up version of WC this week. So far the bad guys have managed to knock one player unconcious, once. I believe we still have one PC who has yet to take damage.

With the downloadable supplement’s section on scaling for an upper level party for reference, I did the following:

I, too, recently began an Ages of Worms adventure with 7 players using a 32-point buy. My group is mostly very experienced players. We are finishing a scaled-up version of WC this week. So far the bad guys have managed to knock one player unconcious, once. I believe we still have one PC who has yet to take damage.

With the downloadable supplement’s section on scaling for an upper level party for reference, I did the following:
** spoiler omitted **

Yup, I'd looked up the details on the downloadable supplement too, and I'm going to be making most of these changes. Additionally, since the characters seem to have quite a bit of muscle and mystical firepower, I'm increasing beastie hit points from average to 75% of max.

Also, I'm starting up a Campaign Journal to track their progress. So far, they've made it through my ad hoc prelude, found the map to the Whisphering Cairn, and are currently on their way back to Diamond Lake with swag to recover and equip.